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<!--
https://bugzilla.mozilla.org/show_bug.cgi?id=719515
-->
<title>Test for Bug 719515</title>
<script src="/tests/SimpleTest/SimpleTest.js"></script>
<link rel="stylesheet" href="/tests/SimpleTest/test.css">
<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=719515">Mozilla Bug 719515</a>
<p id="display"></p>
<div id="content" style="display: none"></div>
<pre id="test">
<script>
getSelection().collapse(document.body, 0);
var range = getSelection().getRangeAt(0);
getSelection().extend(document.body, 1);
isnot(range, getSelection().getRangeAt(0),
      "extend() must replace existing ranges, not mutate them");
range = getSelection().getRangeAt(0);
getSelection().extend(document.body, 1);
isnot(range, getSelection().getRangeAt(0),
      "extend() must replace existing ranges, not mutate them (even for no-op extend()s");
</script>
